1. Field of the Invention
The present invention relates to a wafer polishing device for polishing a wafer by Chemical Mechanical Polishing (CMP).
2. Description of the Related Art
In wafer polishing by CMP, polishing is accomplished by pressing a wafer held by a carrier against a polishing pad while supplying a mechano-chemical abrasive to the rotating polishing pad. In this process, the wafer is polished while being surrounded by a retainer ring, and therefore, it is possible to prevent the wafer under polishing from popping out of the carrier.
Since the retainer ring is pressed to the polishing pad together with the wafer, the retainer ring wears out from use. Hence, the retainer ring needs to be replaced periodically.
Conventionally, a retainer ring is bonded to a backing material, which is placed on a carrier, with adhesive and so on. When the retainer ring is replaced, a part of the carrier is removed from a device body and is replaced together with the backing material.
Alternatively, a retainer ring is attached to a retainer ring attaching part, which is formed on a carrier or a head body, using bolts.
However, it is quite troublesome to attach and detach the above conventional configuration for attaching a retainer ring. Hence, replacement of a retainer ring has required much work and a long time.
The present invention has been developed in view of the above-mentioned circumstances, and its object is to provide a wafer polishing device in which a retainer ring can be attached and detached with ease.
In order to attain the above object, the present invention is directed to a wafer polishing device which polishes a wafer by pressing the wafer against a rotating polishing pad, the wafer polishing device comprising: a wafer holding head having a head body which holds the wafer; and a retainer ring attached to the head body, the wafer being surrounded by the retainer ring, wherein fitting parts are formed respectively on an outer periphery of the head body and an outer periphery of the retainer ring, and a snap ring is fitted to the fitting parts, so that the retainer ring is attached to the head body with the snap ring.
According to the present invention, the retainer ring is in contact with the lower part of the head body and is attached to the head body by fitting the snap ring to the fitting part formed on the outer periphery of the retainer ring and the fitting part formed on the outer periphery of the head body. Hence, the retainer ring can be attached with ease.